Dresden 2014 – scientific programme
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O: Fachverband Oberflächenphysik
O 60: Graphene: Electronic Properties (O jointly with DS, HL, MA, TT)
O 60.5: Talk
Wednesday, April 2, 2014, 17:00–17:15, WIL C107
Scattering mechanisms in Tl-doped epitaxial graphene — •Carola Straßer1, Bart Ludbrook2, Andrea Damascelli2, Christian R. Ast1, and Klaus Kern1,3 — 1Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany — 2Quantum Matter Institute, UBC, Vancouver, BC V6T 1Z4, Canada — 3Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
Since the charge carrier density in graphene can very easily be tuned by means of chemical doping this approach counts as a promising way to design graphene-based future electronic devices. It was shown [1] that the Fermi level can be shifted over a wide range in either direction. But one has to consider that the dopants do not just donate or take the electrons but they have an impact on the electronic structure: they act as scattering centres and change the charge carrier mobility.
We investigated small amounts of Thallium atoms on a monolayer of epitaxial graphene by angular resolved photoemission spectroscopy and did a careful analysis of the line width. Although Tl is very weakly bound and at first sight a paradigm long-range scatterer, we found that it introduces a sizeable short-range contribution. Only by using a model which combines both, long-range and short-range scattering we were able to describe our observations. This allowed us to put an upper limit on the dielectric constant for Tl-doped epitaxial graphene.
[1] H. Liu et al., J. Mater. Chem. 21, 3335 (2011)